Spiral paraffin scrapers



Feb 31956 D. R. TRIPPLEHORN SPIRAL PARAFFIN SCRAPERS Filed June 1, 1953DA v/DRfIk/PPL EHO/EN INVENTOR ATTORNEYS United 1 atent O 'ce SP PFINscans David R. Tripplehorn, Fort Worth, Tex., assignor to James C.Tripplehorn, Pampa, Tex.

Application June 1, 1953, Serial No. 358,849

5 Claims. (Cl. 166-176) My invention is an improved spiral parafiinscraper of the type which grips a sucker rod and is maintained inposition thereon by friction.

The principal object of my invention is to provide a spring steel spiralparafiin scraper which may be quickly and easily installed on or removedfrom a sucker rod by any member of a drilling crew at the well site.According to a recent survey made of the oil industry it appears thatthe most common type of parafiin scraper is the type shown in Patent No.2,453,199, this scraper being secured in place by welding. Because ofthe fact that the welding of the ends of the scraper to a sucker roddestroys the temper of the rod in the vicinity of the weld,

it is not practical to attempt to weld a scraper to a rod at the wellsite, and it is therefore necessary and common practice to ship thesucker rods to an installation factory where metal bands are shrunkaround the rods, the scrapers being subsequently welded to these bandsinstead of to the rods. I have therefore provided the paralfin scraperwhich is the subject of the present patent application and which isentirely satisfactory to both the well operators and to themanufacturers of the sucker rods. My invention eliminates the necessityof shipping the rods to an installation factory for installation ofscrapers, and at the same time provides a paraffin scraper which,according to actual tests, grips the rods so tightly that a' force, wellin excess of those encountered in normal well operations, is required tocause the scraper to slip on the rod. The elimination of the necessityof shipping sucker rods to installation factories to have scraperswelded thereon effects a considerable saving in cost and time.

Another very important object of my invention is to provide a paraffinscraper which will not nick or bite into the sucker rod in the mannerintended and set forth in some prior-art disclosures, showing a spiralparaffin scraper having each end turned in so as to bite into the rod.Such a bite into the rod by the end of the scraper, of course, increasesthe grip of the scraper on the rod, but the nicking of the rod causesfrequent breakage thereof by creating a weak spot therein. Consequentlythis type of scraper is definitely not recommended by manufacturers ofthe drill rods, and, in fact, has apparently not been marketed at all.

Another important advantage of my paraflin scraper is that, since thelatter is installed at the well site, the spacing between adjacentscrapers may be altered to suit the length of stroke of the particularpump which is used, thereby obviating the disadvantage of the type ofparaflin scraper which is welded to the sucker rod which can not belongitudinally repositioned at the site of the drilling operation, andcan not be transferred to a new rod from a damaged one.

Another important object of my invention is to provide a spiral parafiinscraper which may be economically manufactured of heat treated springsteel, the present practice being to use No. 1095 spring steel having aRockwell hardness of 43 when heat treated.

2,733,768 Patented Feb. 7, 1956 The principal feature of novelty of myinvention resides in the ends of the scraper which, like the body of thescraper, are substantially rectangular in cross-section and which areperpendicularly disposed with respect to the surface of the rod. It isan important object of my invention to provide a paraflin scraper havingends which are each tapered both inwardly and outwardly in a directionradially of the rod as shown in the accompanying drawing. Each end ofthe scraper is tapered inwardly so as to prevent the end from engagingon tool joints in the well tubing; and in addition, the inside edge ofeach end of the scraper is tapered outwardly from the surface of thesucker rod so as to insure that the frictional gripping of the helix ofthe scraper on the sucker rod will occur and will be uniform along theentire inner periphcry of the scraper intermediate its tapered ends.Otherwise the inner periphery of the helix may be bowed outwardly fromthe rod somewhere along the line of contact caused by distortion of thehelical shape of the scraper when one or both ends bite into the rod.The tapering of the inner periphery at the ends assures that there willbe no inwardly projecting discontinuities.

Another advantage of tapering the end of the scraper outwardly from thesurface of the sucker rod is to pro- ,vide a small clearance at each endbetween the inner periphery of the scraper and the surface of the suckerrod so that a screw-driver or other tool may be inserted therebetweenfor the purpose of removing the scraper from the rod.

Another very important object of my invention is to i provide a scraperhaving ends which are not bent very far from the original shape of thebar stock prior to shaping of the helical scraper. It has been foundthat, during the manufacture of spiral scrapers wherein each end of thescraper is bent through a considerable angle so as to provide hookedends such as are shown in some prior-art disclosures, when this type ofscraper was tested in actual operation within oil wells, the endsfrequently break off of the scraper and not only reduce the grippingpower of the scraper but also tendto wedge between moving parts withinthe well and cause damage to the tubing and sucker rod or to theremaining portion of the scraper. Further tests were run in order todetermine the cause of such breakage and it was discovered that thebreakage was due to the complex bending of the ends of the annealed barstock during shaping of the scraper and prior to final heat treatingthereof. It the ends of the scraper are bent very sharply or in severaldifferent directions, the grain structureof the annealed spring steel isoverstressed in such a way as to cause hidden damage thereto. Myinvention eliminates most of this complex bending of the ends of thescraper so that the device set forth in the present application hassubstantially as strong a grain structure at its ends as it haselsewhere along its length.

Another important object of my invention is to provide a helical scraperhaving its end portions lying in a continuation of the helical form ofthe body of the scraper so that there are no complex bends whichincrease turbulence in the flow of the oil therepas t, such turbulencegreatly restricting the flow of fluid upwardly through the tubing.Parafiin tends to build up on complex bends to the extent that free flowof well liquid is retarded.

Another advantage of my scraper is that since the ends thereof conformwith the helical shape of the body of the scraper, it is possible tonest more of these scrapers together for the purpose of shipment than ispossible with scrapers of the type wherein the end structure of thescraper does not conform withthe helical shape of the body and therebyprevents nesting of a large number of scrapers together for shipment.

Ether objeets'and- 'advantages of my invention will become.apparentduring the. following .discussion. of the drawing wherein:

Figure 1 is a longitudinal view of a pump tubing, broken away toshownthesucker rodwithinsaid tubing having-one of my spiral paraffinscrapersfixed thereto.

:Fig. 2 is an enlarged-section viewalong line 2-2' of Fig. 1.

. --Fig. 3 is -an enlarged view of one end of my spiral paraffnscrapersecured to the sucker rod.

Fig. 4 is asection view along line44 of Fig. 3.

Fig.. 5 is a view of one end of the rectangular spring steel stock fromwhich my parafiin scrapers are made, this view showingthe-end of the rodtapered at an angle of approximately for the purpose hereinafterdiscussed.

.Refer-ring-nowthe drawing, Figs. land 2 showa'pump tubing T having -asucker rod R axially disposed therein, the tubing and therod-beingstandard equipment and forming no part .of the presentinvention. A spiral parafiin'scraper 1, according to the-presentinvention, is shown frictionally gripping therod R, the scraper havingidentical upper and lower'ends. Each of these ends is tapered inwardlytowardthe rod R as at 2 so as to prevent snagging of the scraper on'the'joints of the tubing T, and each end of the inner-periphery of thespiral scraper is tapered outwardly fromthe-rod R as at 3, forthepurpose hereinafter stated; Attention is'called to the fact that eachend of "the paraflin-scraper conforms with the general'helical form ofthe body of the scraper and is a continuation thereof so that theparaffnscraper endsare perpendicular to the-adjacent surface of thesucker rod and do not tend to turn over or lie flat thereagainst. The"fact that thescraper ends conform to the general helical shape of thebody of the scraper-permits the spiral flow of well fluids to washallexposed surfaces of the scraper and the rod to prevent the building upofparaflin deposits.

The p'araflin scraper itse'lf is manufactured-from substantiallyrectangular 1095 spring steel stock, which stock has been cut at eachend in the manner shown in "Fig. 5 so as to provide at the terminalportions'of the stock an'approximate 10 angle before thestock is formedinto'the helix. After the spring steel stock In is formed into thehelical shape, the outer surface of the stock at the ends thereof in thevicinity of 2a, Fig. 5, is bent slightly inwardly so that the taperedsurface 3a partially approaches the inner periphery of the helix. Inthis manner both the inner andtheouter edges of the ter- 'minal portionsofthe'scraperare shaped with a minimum bending" of the annealed springsteel.

During the forming of the spring steel flatstock 1a intothehelicalscraper 1, the inner periphery 4 of the helix isformed'to'provide a uniform diameter somewhat less than theouter'diameter of-the sucker rod which the scraper is intended to grip,and this inner diameter is "uniform along the full lengthofthe'scraperbetween the "tapered ends3 so that the grip of the scraperon the-sucker -rod will be uniform along substantially its full-lengthexcept at the terminal ends which do not contact therod.

In operation disturbed; 'F- SeVere. stresses :occur tending to :stretchsiwkerarods whenxaipiunp.fails tor-sandsup. 'When a rod is stretched bya pulling rig tryingtofree a-stuckplunger,

tapered respectively towardeach other, said terminaltpor- 'tions formingcontinuations of the spiral shape ofzsaid d the diameter of the rod isdecreased enough to permit a scraperto slide thereon and approachanadjacent scraper.

My scraper is quickly and easily installed on a sucker rod withoutnecessitating special tools, such installation being carried out merelyby hand with the assistance of a screw-driver or tire iron to maintainone end of the scraper in place on the rod while the body of the scraperis manually wound therearound. When one end and the body of the scraperare secured in place, the other end of the scraper may be positioned byplacing a screw-driver under that end and against the rod and snapping.theend in place on the rod. Removal of the scraper from the rod, ofcourse, is easily accomplished by merely sliding a screw-driver betweenthe sucker rod and the inner periphery 3 of one end of the'scraper andprying that end of the scraper off of the rod, the disengagement of thebody of the scraper being easily accomplished by manual unwindingthereof.

Tests of actual production models of this scrapershow thatit grips thesmoker rod so tightly that a force of 2350 pounds is required to causeslippage thereofon the rod, and testsmade during actual operation inwells show that even after a rod has been stressed orstretched so thatits diameter is slightly reduced, my paraifn scrapers do not slip-on therod under normal operating conditions.

I do notlimit my invention to the exact form shown in the drawing, forobviously changes may be madetherein within thescope of the claims.

ing-opposed narrow edges and being wound in the form of a helix, saidblade frictionally engaging said-rod along'one narrowedge and standingnormal to said-rod along the full length of the scraper, the said narrowedges being tapered at the ends of said scraper to partially. approacheach other.

2. A removable spiral parafiin scraper adapted to frictionallyengage asucker rod'within the tubing ofa well,

.said .scrapercomprising a spiraled blade of spring material having'aninner periphery defining a bore through the scraper, the bore beingnormally of smaller diam- 'eter than the diameter of the sucker rodwhereby said 'inner periphery will tightly grip said rod when thescraper is engaged thereon, said blade being of helical shape andbeingdisposed normal to said rod along the full length of the scraper, andthe-inner peripheryat the ends of the scraper being tapered outwardlyaway from the rod whereby the ends of the scraper will be prevented frombiting into said rod.

. In-a scraper as set forth in-claim 2, said blade having an outerperiphery, and the outer peripherywbeing tapered inwardly toward .saidrod at the ends of the scraper to prevent snagging of the scraper insaid,tubing.

4. A'spiral'parafiin scraper adapted to engage a sucker rod within thetubing of a well through which :tubing fluid is-fiowing, said scrapercomprising-a spiraled blade of spring material having narrow surfacesforming respectively the outer-and inner peripheries of thescraper saidinner periphery frictionally gripping saidsucker rod, and said bladehaving broad surfaces disposed substantially-normal to said rod alongthe full length of. said scraper, and each-end of said-blade havingaterminal portion whereat said inner -.and outer peripheries rare bodyto therebypresenta minimum impedance to:.the flow of said fluid.

5. -A spiralparaflin scraper adapted to engage azsucker rod within thetubing of a well, saidscraper=comprising a spiraled blade of springmaterial substantially rectan- 'guiarin cross section, said blade havingnarrow surfaces forming respectively they outer ,andinner peripheries ofthe scraper said inner periphery frictionally gripping said sucker rod,and said blade having broad surfaces disposed substantially normal tosaid rod along the full length of said scraper, and each end of saidblade having a terminal portion whereat said inner and outer peripheriesare tapered respectively toward each other 5 thereby tapering theterminal portion of the outer periphery inwardly toward the rod toprevent snagging of the ends against said tubing and tapering theterminal portion of the inner periphery outwardly away from the rodwhereby the grip of the scraper on the rod will occur 10 intermediatesaid terminal portions.

References Cited in the file of this patent UNITED STATES PATENTS

1. A REMOVABLE SPIRAL PARAFFIN SCRAPER ADAPTED TO FRICTIONALLY ENGAGE ASUCKER ROD WITHIN THE TUBING OF A WELL, SAID SCRAPER COMPRISING A BLADEOF SPRING MATERIAL HAVING OPPOSED NARROW EDGES AND BEING WOUND IN THEFORM OF A HELIX, SAID BLADE FRICTIONALLY ENGAGING SAID ROD ALONG ONENARROW EDGE AND STANDING NORMAL TO SAID ROD ALONG THE FULLL LENGTH OFTHE SCRAPER, THE SAID NARROW